What happened
On 4 June 2004, an Airbus A310-301, registration EI-JFK, was performing a scheduled flight from Dublin Airport to New York. During the takeoff roll on Runway 28, the aircraft's systems triggered an Exhaust Gas Temperature (EGT) over-limit alert and a nacelle temperature indication. Shortly after rotation, the crew received a fire warning for the number 2 engine.
In response to the emergency, the flight crew declared an emergency, notified Air Traffic Control, and shut down the affected engine. The captain activated the onboard fire suppression system and requested that emergency services be on standby. The aircraft performed an automated autoland and touched down safely on Runway 28. There were no injuries among the 303 passengers or the 12 crew members on board.
The investigation
Following the incident, engineers inspected the aircraft and identified a leak in a pneumatic duct within the number 2 engine. This leak allowed high-temperature air, exceeding 600ºC, to escape into the engine core compartment, causing heat damage to the electrical harness.
Technical examinations focused on a V-band clamp at the 14th Stage Manifold. Investigators found that a portion of this coupling had detached. Laboratory analysis using scanning electron microscopy confirmed that the coupling failed due to a fatigue fracture caused by prolonged cyclic tension loading. Further inspection of the Tolerance Take-up (TTU) unit revealed that the lockwire securing the adjustment sleeves had failed, which allowed the adjustment rings to rotate and the sleeves to extend until the threads disengaged. This disengagement left the inner duct unsupported and caused the manifold to become misaligned.
Findings
- The primary cause of the coupling failure was in-service wear within the TTU components and the subsequent failure of the TTU wire locking.
- The failure of the lockwire allowed the adjustment rings to rotate, leading to the over-extension of the TTU.
- The resulting disengagement of the adjustment sleeves left the inner duct unsupported, creating tension loading on the 14th Stage Manifold coupling, which initiated the fatigue fracture.